本文選題：高強度聚焦超聲 + 微泡造影劑��； 參考：《天津醫(yī)科大學(xué)》2017年碩士論文

【摘要】：近年興起的無創(chuàng)或微創(chuàng)高強度聚焦超聲腫瘤治療方法受到眾多研究者的關(guān)注。該治療方法是將人體外發(fā)射的低功率密度超聲波聚焦到人體內(nèi)腫瘤部位,通過組織吸收超聲波能量而使腫瘤組織溫度在短時間內(nèi)達到60℃以上凝固性壞死的一種療法。該療法在治療人體深部腫瘤時,由于聲波需傳播的距離較遠且傳播途中可能需穿過強衰減的骨骼組織,使超聲能量大幅度衰減出現(xiàn)焦點能量不足,無法凝固性致死腫瘤組織的問題,同時HIFU一次性形成的可治療焦域體積一般較小,對于大體積腫瘤治療時采用焦域多次疊加進行,所需治療時間長并可能引發(fā)并發(fā)癥。為了安全有效地治療人體深部腫瘤和大體積腫瘤,焦域能量不足和治療時間過長是HIFU臨床治療的迫切需要解決的問題,具有HIFU治療增效作用的超聲微泡造影劑受到眾多研究者的關(guān)注。目的為了安全有效地利用HIFU治療人體深部腫瘤和大體積腫瘤,解決焦域能量不足和治療時間過長等問題,眾多研究者提出利用微泡造影劑增效HIFU治療效果。本研究建立仿組織數(shù)值仿真模型,采用數(shù)值仿真法對不同條件下的焦域分布進行仿真研究,通過分析討論換能器輸入功率、工作頻率、仿組織體模參數(shù)和微泡初始分布條件對HIFU形成焦域的影響,并以含蛋清和微泡造影劑的仿組織體模為實驗對象加以驗證,為微泡造影劑在HIFU臨床治療的應(yīng)用提供參考數(shù)據(jù)。方法本研究結(jié)合凹球面自聚焦超聲換能器結(jié)構(gòu)參數(shù),建立仿組織數(shù)值仿真模型,利用聲傳播方程、生物熱傳導(dǎo)方程、Yang-Church氣泡運動方程,基于圓柱軸對稱坐標系通過時域有限差分(Finite Difference Time Domain,FDTD)法和龍格-庫塔(Runge-Kutta,RK)法數(shù)值仿真HIFU在含氣泡仿組織體模中的聲壓場和溫度場,并以含蛋清和微泡造影劑的仿組織體模為實驗對象,研究對HIFU形成焦域的影響。結(jié)果隨著體模中初始氣體體積分數(shù)的增大,60℃以上焦域體積不斷增大且焦域向靠近換能器方向移動;當氣體體積分數(shù)為2.5×10-6時,在體模表面聚焦未能形成有效焦域。隨著輸入功率的增大,60℃以上焦域逐漸增大,焦域峰值溫度逐漸升高、焦域位置幾乎不變,當功率為30W時數(shù)值仿真所得焦域體積與體模實驗所得焦域體積大小幾乎相同,當功率為40W~60W時數(shù)值仿真所得焦域體積比體模實驗所得焦域體積略小。隨著換能器工作頻率的增大,60℃以上焦域逐漸增大,焦域峰值溫度逐漸升高、焦域向遠離換能器方向移動,焦域的長軸與短軸均隨著工作頻率的升高而增大,且斜率變小。隨著仿組織體模粘度的增大,60℃以上焦域逐漸減小,焦域峰值溫度逐漸降低、焦域向遠離換能器方向移動,焦域的長軸與短軸均隨著粘度的變大而減小。隨著仿組織體模剪切模量的增大,60℃以上焦域先增大后減小,焦域峰值溫度、最大絕對聲壓先升高后降低、焦域位置幾乎不發(fā)生偏移;焦域的長軸與短軸均隨著粘度的變大而先增大后減小。隨著體模中氣泡初始半徑的增大,60℃以上焦域逐漸增大,焦域峰值溫度逐漸升高、焦域向遠離換能器方向移動,焦域的長軸與短軸均隨著氣泡初始半徑的增大而增大,且斜率變小。結(jié)論微泡造影劑可以增大HIFU形成60℃以上的可治療焦域;增大輸入功率、氣泡初始半徑和提升工作頻率均可增大焦域,增大輸入功率,焦域形狀可能發(fā)生變化;升高工作頻率和增大氣泡初始半徑,焦域向遠離換能器的方向移動;仿組織體模的粘度越大,焦域峰值溫度越低、焦域越小、焦域向遠離換能器方向移動;隨著仿組織體模剪切模量的增大,焦域先增大后減小,且向遠離換能器方向移動。
[Abstract]:The recent development of non-invasive or minimally invasive high intensity focused ultrasound therapy has attracted the attention of many researchers. The treatment is to focus the human body's external emission low power density ultrasound to the body of the human body. By absorbing the ultrasonic energy, the tumor tissue temperature can reach more than 60 degrees centigrade in a short time. In the treatment of deep tumors of the human body, the treatment is far away from sound wave and may need to pass through strong attenuation of bone tissue during the transmission, so that the ultrasonic energy is greatly attenuated to the problem of lack of focal energy and the inability to solidify the tumor tissue. At the same time, the disposable focal area of HIFU is formed. In order to treat the human deep tumor and large volume tumor, the insufficiency of the focal area and the long treatment time are the urgent problems to be solved in the clinical treatment of HIFU, with the effect of HIFU therapy. The ultrasonic microbubble contrast agent is concerned by many researchers. In order to use HIFU to treat the deep tumor and large volume tumor in human body safely and effectively, to solve the problem of insufficient energy and long treatment time in the focal area, many researchers have proposed the use of microbubble contrast agent to increase the effect of HIFU in the treatment of fruit. The numerical simulation method is used to simulate the focal region distribution under different conditions. The influence of the input power of the transducer, the working frequency, the parameters of the tissue model and the initial microbubble distribution on the HIFU focal region are analyzed and discussed, and the microbubbles are verified by the imitated fabric model containing the egg white and the microbubble contrast agent. This study provides reference data in the application of HIFU clinical treatment. Method this study combines the structural parameters of concave spherical autofocus transducer, establishes a numerical simulation model of mimic tissue, uses sound propagation equation, biologic heat conduction equation, Yang-Church bubble motion equation, and is based on the finite difference time domain (Finite Difference T) coordinate system based on cylindrical axis. IME Domain, FDTD) method and Runge Kutta (Runge-Kutta, RK) method are used to simulate the sound pressure field and temperature field of HIFU in a bubble imitating tissue model. The effects of the simulated tissue model containing egg white and microbubble contrast medium on the focal region of HIFU are studied. The results are over 60 degrees with the increase of the volume fraction of the initial gas in the body model. When the volume fraction is 2.5 * 10-6, the focal region will not form an effective focal region when the volume fraction of the gas is 2.5 * 10-6. With the increase of the input power, the focal region of the focal region is gradually increased, the peak temperature of the focal region is gradually increased and the focal region is almost unchanged. When the power is 30W, the focal region is obtained by numerical simulation. The size of the focal area obtained by the volume and the body model is almost the same. When the power is 40W~60W, the focal volume of the focal area is slightly smaller than that in the body model experiment. With the increase of the working frequency of the transducer, the focal region above 60 degrees increases gradually, the peak temperature of the focal region increases gradually, the focal region moves away from the transducer direction and the focal region is long. Both the axis and the short axis increase with the increase of the working frequency, and the slope decreases. With the increase of the viscosity of the imitated tissue, the focal region of the focal region decreases gradually, the peak temperature of the focal region decreases gradually, the focal region moves away from the transducer direction. The long axis and the short axis of the focal region decrease with the increase of the viscosity. With the shear modulus of the imitated tissue die. The focal region above 60 C increases first and then decreases, the peak temperature of the focal region increases first and then decreases, and the focal region is almost no offset; the long axis and the short axis of the focal region increase first and then decrease with the increase of the viscosity. With the increase of the initial bubble radius in the body model, the focal area above 60 degrees increases gradually, the peak temperature of the focal region is heated by the temperature. Gradually, the focal region moves away from the transducer direction. Both the long axis and the short axis of the focal region increase with the increase of the initial radius of the bubble, and the slope becomes smaller. Conclusion the microbubble contrast agent can increase the HIFU formation of the treatable focal region above 60 degrees C. The increase of the input power, the initial radius of the bubble and the lifting frequency can increase the focal region and increase the input power. In addition, the shape of the focal region may change, and the working frequency and the initial radius of the bubble are increased, the focal region moves toward the direction of the transducer, the greater the viscosity of the model, the lower the peak temperature of the focal region, the smaller the focal region and the direction of the focal region moving away from the transducer, and the focal region increases first and then decreases with the increase of the modulus of the imitated fabric. Move away from the transducer direction.
【學(xué)位授予單位】：天津醫(yī)科大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：R730.5;TB552

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